Fairchild 692 (Published documents)

[ForthMonkey]

I found some Fairchild schematics.Solid-state and easy schematics.Made di-box.And now making preamp.

I will make some 692 modules.

Think it as gain module.22dB to 52dB.Changed original transistors.Breadboarded it and working well.To make it mic pre,need 1:5 transformer and mic pre front end.

Original schematic

https://dl.dropboxusercontent.com/u/91809016/Fairchild%20692/Fairchild_692AA.pdf

I made selectable input and output transformers.

If you want to use it with only one transformer,do not install Control Board.Just use simple frontend.And use RZ and CZ components to make zobel.

If you use all transformers,do not install RZ and CZ.Install seperate zobels to directly transformers's pins.

Single sided self etch files...

PRE BOARD

Schematic

https://dl.dropboxusercontent.com/u/91809016/Fairchild%20692/PRE_SCHEMATIC.pdf

Bottom

https://dl.dropboxusercontent.com/u/91809016/Fairchild%20692/PRE_BOTTOM.pdf

Layout

https://dl.dropboxusercontent.com/u/91809016/Fairchild%20692/PRE_LAYOUT.pdf

CONTROL BOARD

Schematic

https://dl.dropboxusercontent.com/u/91809016/Fairchild%20692/CONTROL_SCHEMATIC.pdf

Bottom

https://dl.dropboxusercontent.com/u/91809016/Fairchild%20692/CONTROL_BOTTOM.pdf

Layout

https://dl.dropboxusercontent.com/u/91809016/Fairchild%20692/CONTROL_LAYOUT.pdf

 

[ruffrecords]

You might like to add a resistor ground at the input and one at the output just to make sure the input and output caps get charged up  even if nothing is connected to the board.

Cheers

Ian

 

[ForthMonkey]

You might like to add a resistor ground at the input and one at the output just to make sure the input and output caps get charged up  even if nothing is connected to the board.

Cheers

Ian

Thanks! I will try this trick.Resistors should be after caps,right?And how to select resistors values?

 

[ForthMonkey]

Updated!